1. Field of the Disclosure
The present disclosure relates to an adhesive coating apparatus and method for coupling two substrates of a display panel, and to a display panel using the same.
2. Related Art
Recently, display devices are being developed having various functions, in addition to a function of simply displaying an image, added thereto. As a type of display device, display devices with a touch screen function (enabling the direct input of information through a screen) added thereto are being actively developed. As the display devices, there are liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission display (FED) devices, and light emitting display devices. Among such display devices, the LCD devices are easily manufactured, have good drivability of drivers, and realize a high-quality image, thus are popular.
The LCD devices display a moving image by using thin film transistors (TFTs) as switching elements. The LCD devices are used as display devices for notebook computers, tablet computers, navigations, and various portable information devices, in addition to televisions or monitors.
A liquid crystal display panel applied to the LCD devices includes an upper substrate and a lower substrate coupled to the upper substrate. A liquid crystal layer is formed between the upper substrate and the lower substrate. Also, a touch substrate may be adhered to a top of the upper substrate or a bottom of the lower substrate in order for the liquid crystal display panel to have the touch screen function.
FIG. 1 is a view for describing problems of a related art display panel, and FIG. 2 is a view showing an adhesive layer having lumps in the related art display panel.
Referring to FIG. 1, a related art display panel 100 includes a first substrate 110 and an adhesive layer 140 formed on the first substrate 110.
The adhesive layer 140 adheres the first substrate 110 to a second substrate (not shown) facing-coupled to the first substrate 110.
The adhesive layer 140 is formed by coating an adhesive along a coating line 130. The coating line 130 has a first straight section 131, a second straight section 132 vertical to the first straight section 131, and a corner section 133 connecting the first straight section 131 and the second straight section 132.
In a process that forms the adhesive layer 140 in the related art display panel 100, the adhesive layer 140 is formed by coating an adhesive in the order of the first straight section 131, corner section 133, and second straight section 132.
That is, as illustrated in the drawing, the adhesive is first coated on the first straight section 131, coated on the corner section 133 subsequently thereto, and then coated on the second straight section 132 in a changed direction.
In a process of coating the adhesive along the coating line 130, due to a shape of the coating line 130, the adhesive is inevitably coated on the corner section 133 two times.
Specifically, the adhesive is coated such that the adhesive layer 140 has the same thickness in the first straight section 131, second straight section 132, and corner section 133. Therefore, the same amount of adhesive as the first and second straight sections 131 and 132 is coated on the corner section 133 two times. As a result, a thickness of the adhesive layer 140 in the corner section 133 is inevitably thicker than the first and second straight sections 131 and 132. Alternatively, a height of the adhesive layer 140 in the corner section 133 is inevitably higher than the first and second straight sections 131 and 132.
For these reasons, the related art display panel has the following disadvantages. When the first substrate 110 is being coupled to the second substrate (not shown), the adhesive layer 140 in the corner section 133 is spread by being pressed by the first substrate 110 and the second substrate (not shown). An active area displaying an image is formed in a central portion of the display panel 100, but the adhesive layer 140 in the corner section 133 is spread to cover the active area. This is because the adhesive is coated two times, and thus, the adhesive layer 140 becomes thicker or higher, unlike the first straight section 131 and the second straight section 132. As a result, the adhesive layer 140 covers a portion of an image displayed by the display panel, causing a reduction in quality of an image displayed by the display panel 100.
Moreover, if the adhesive layer 140 in the corner section 133 is spread to outside the first substrate 110 and hardened, it is required to separately perform a process that, after the first substrate 110 is coupled to the second substrate (not shown), removes the adhesive layer 140 hardened at an outer side of the first substrate 110. In this case, a process of manufacturing the display panel 100 becomes complicated, and a productivity of the display panel 100 decreases.